The difference is that ‘color-blind’ liberals who co-opt the language and appearance of the civil rights movement without actually understanding or living the ideals behind it were the target of the joke, it wasn’t supposed to be funny just because it was blackface. I feel that the backlash to that movie is 100% the result of a lack of media literacy. Like, it’s not Citizen Kane, but to accuse Downey Jr. of racism for taking that role is to miss the point so hard it’s hard to imagine that the people who feel that way watched the same movie that I did. You have to be coming from a place of total refusal to engage with the subtext (or really just the text, absolutely nothing about Tropic Thunder is subtle in the least) of the work, and an axiomatic understanding of certain actions as always-racist without regard for context.